What happens to a building after an earthquake?

Structural vibrations: a wide spread problem

Earthquakes are one of the most destructive natural disasters, they can cause significant damage to built-up structures, profoundly altering the urban and social fabric. The force of these seismic events can provoke damage ranging from slight cracks in the foundations and walls to collapses of entire buildings, endangering the lives and safety of residents.

Building response to seismic stress

When an earthquake occurs, seismic waves propagate through the soil, causing the shaking of the ground. This movement is transferred to buildings, that start vibrating too. Each building has its own natural vibration frequency, influenced by height and structural characteristics. In general, lower buildings have higher natural frequencies, while higher buildings have lower natural frequencies. If the frequency of the seismic waves coincides with the natural frequency of the building, the phenomenon of resonance can occur, amplifying the oscillations and increasing the risk of structural damage.

Types of damage of buildings during an earthquake

The damage to buildings caused by an earthquake can be classified into two main categories: structural damage and non-structural damage.

• Structural damage: it concerns the supporting elements of the building, such as pillars, beams and load-bearing walls. This damage can compromise the stability of the entire structure, leading in some cases to the total collapse of the building. For example, the formation of a “soft floor” occurs when one floor of the building has significantly lower stiffness than the others, often due to large windows or open spaces on the ground floor, making it more vulnerable during an earthquake.

• Non-structural damage: this type of damage affects elements such as external claddings, internal partitions, suspended ceilings and installations. During an earthquake, the deformation of the structure can cause these components to break or detach. For example, external buffers, often consisting of “box” walls with an air chamber for thermal insulation, can be damaged or collapse, posing a serious danger to the occupants. In addition, the “bursting” of the ceiling, ie the collapse of portions of the ceiling such as plaster or bricks, is another typical damage caused by the earthquake.

Factors affecting the seismic vulnerability of buildings

The seismic vulnerability of a building depends on several factors:

• Construction type: non-reinforced masonry buildings are generally more vulnerable than reinforced concrete or steel buildings.
• Age and maintenance status: older or poorly maintained buildings may show deterioration of materials, reducing their ability to withstand seismic stress.
• Soil characteristics: the nature of the soil on which the building is built has a significant influence on the seismic response. Soft or liquefied soils can amplify seismic waves, increasing the risk of damage.

ISAAC AMD system for reducing seismic vulnerability

The Active Mass Dampers (AMDs) developed by ISAAC are a technological innovation for seismic risk reduction. These devices, which can be installed in existing buildings without invasive intervention, significantly reduce seismic oscillations. The AMDs are powered by an intelligent system that detects the movement of the structure in real time and generates contrasting forces to dampen vibrations. This helps to limit structural and non-structural damage, improving the safety of buildings and protecting people inside. The use of these systems represents an innovative solution for the protection of the building heritage in areas with high seismicity.

Do you want to protect your building from seismic risks?

Learn how ISAAC’s AMD systems can improve the safety of your facility by reducing oscillations and preventing structural and non-structural damage.

Book a dedicated consultancy

As a designer or engineer, would you like to learn about integrating Active Mass Dampers into your projects?

🔹 Contact us 🔹